摘要:

High crystalline quality &ggr;‐Al2O3films were epitaxially grown on Si(111) substrates at low growth temperatures from 750 to 900 °C by Al solid source andN2Ogas molecular beam epitaxy. Very thin &ggr;‐Al2O3films grown at 850 °C showed streaky reflection high‐energy electron diffraction patterns. Byinsitux‐ray photoelectron spectroscopy measurements, carbon contamination, as is seen in the films grown withAl(CH3)3source, was not detected within the sensitivity. The stoichiometry of the growth films was found to be similar to that ofAl2O3. Growth rates of epitaxial &ggr;‐Al2O3layers were found to decrease with increasing growth temperatures. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115102

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Two‐dimensional diffusion of holes is studied inn‐type InGaAs heterostructures by frequency dependent measurements of the photoresponse in the periphery of a mesa diode. An analytical theory is presented that gives the spatial and frequency dependent photoresponse. Measurements agree well with theory and establish a hole diffusion length of 60 &mgr;m, a hole recombination lifetime of 3 &mgr;s, and a hole mobility of 480 cm2/V s for our material. An upper limit is also established for the recombination velocity at the InP or InGaAsP heterointerfaces. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115103

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Isothermal electron beam heating has been used to anneal ion‐implanted silicon samples and the changes in the spectral &Vegr;(&lgr;,T) and total hemispherical &Vegr;Tot(T) emissivities caused by damage annealing and dopant activation have been monitoredinsitu. Free carrier absorption effects have been observed after annealing of a B‐implanted sample, resulting in an increase of &Vegr;(&lgr;,T) in the semitransparent region and an increase of &Vegr;Tot(T). An increase of normalized emissivity at 800 °C was also observed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115104

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The alignment of the electronic band structures at contacts between solids is defined by the continuum of interface‐induced gap states and the charge transfer across the interface. The barrier heights of metal–semiconductor contacts as well as the band edge discontinuities of semiconductor heterostructures are primarily described by the zero‐charge‐transfer barrier heights. This characteristic semiconductor property equals the energy distance between the majority‐carrier band edge and the charge‐neutrality level of the interface‐induced gap states. The compositional trends of barrier heights of Al1−xInxAs, In1−xGaxAs, and Al1−xGaxAs Schottky contacts and of valence‐band offsets of Al1−xGaxAs/GaAs heterostructures are analyzed. The zero‐charge‐transfer barrier heights of ternary compounds are found to vary linearly as a function of the compositional parameterx. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115105

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We systematically analyze the stress‐strain‐temperature relationships and include thermal strain contributions to the misfit‐strain only formalism of strained‐layer heterostructures. Application of this theory to the GexSi1−x/Si (100) and InxGa1−xAs/GaAs (100) system demonstrates that the thermal effect lowers the critical layer thickness significantly on both systems, in excellent agreement with experimentally measured values. Empirical formulae of the critical layer thickness in terms of a mole fraction and temperature for these systems are provided. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115106

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Doping of the nanocrystalline‐Si/SiO2composite material with tungsten results in a quenching of the ‘‘red’’ photoluminescence (PL) and an appearance of an intense blue/violet one with a spectral maximum around 2.8 eV and decay time of ≤3 ns. Unlike the green/blue PL from silanol groups, this PL is stable upon annealing and does not show any polarization memory. A possible mechanism of this PL is suggested. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115107

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report the demonstration of normal incidence infrared (3–5 &mgr;m) electroabsorption modulation utilizing the Stark effect to induce &Ggr;‐Ltransitions in asymmetrically stepped AlSb/InAs/Al0.4Ga0.6Sb/GaSb/AlSb quantum wells grown on a GaSb substrate by molecular beam epitaxy. The measurements were performed using a Fourier transform infrared spectrometer at 77 K. The largest infrared absorption at 5 &mgr;m with an absorption coefficient of 3200 cm−1has been obtained at 14 V reverse bias. The results indicate the potential of this novel structure for application as a normal incidence infrared modulator. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115108

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We study single‐carrier traps in a GaAs/AlxGa1−xAs heterostructure by observing random telegraph signals (RTSs), which are caused by the traps having energy levels within a fewkBTof the Fermi level. RTSs are observed in a split gate device while a narrow channel is shifted by independently controlling the voltage applied to each part of the split gate. This measurement reveals the variations of the energy levels of traps with the channel position. From these variations the locations and the energy distributions of the traps are demonstrated. The strength of the confinement potential around the trap is also discussed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115109

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A novel misalignment offset reduction technique is extended in order to separate a piezoresistive voltage, from the Hall voltage, in doubly connected Hall elements based on silicon. In a special configuration, this method exploits directional averaging using biaxial current injection from four electrically separate current sources in order to cancelinsituthe stress‐generated off‐diagonal piezoresistive voltage across the Hall voltage contacts. Measurements suggest field‐equivalent offsets below 1 mT in (001) surfacen‐Si devices with current injection in the [110] direction. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115110

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Metalorganic molecular beam epitaxy of carbon‐doped heterostructures and InP/Ga0.47In0.53As heterostructure bipolar transistors using carbontetrabromide (CBr4) as the dopant source is reported. Secondary ion mass spectrometry show H incorporation associated with the carbon doping. Hall data for as‐grown and postgrowth annealed samples showed a clear increase in doping only for samples grown at the lowest temperature, 450 °C, and higher doping levels. An increase in the mobility, however, was measured for nearly all samples after annealing, indicating that the neutral C–H complexes most likely contribute to majority carrier scattering. The gain variation for various devices with base thickness,WB, and base doping,p, was found to be nearly proportional to 1/(WB×p)2consistent with diffusive base transport and Auger dominated recombination in the heavily doped base region. It was also observed that in devices where the C‐doped base was grown at temperatures ≳500 °C, the gain was shifted to much lower values possibly indicating a reduced electron carrier lifetime. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115111

出版商:AIP    

年代:1995

数据来源: AIP